Practice question

Genomic imprinting represents epigenetic phenomenon where allele expression depends on parental origin due to differential DNA methylation marks established during gametogenesis in sperm and egg. Imprinted genes carry methylation imprint silencing one parental copy permanently in somatic cells, so only maternal or paternal allele transcribes in offspring tissues like placenta and brain. This parent-specific monoallelic expression regulates growth, metabolism, and neurodevelopment. Loss of imprinting regulation leads to dosage abnormalities causing disorders like Angelman, Prader-Willi, Beckwith-Wiedemann, highlighting importance of parental-origin-dependent expression beyond Mendelian rules.